The identification of the fluids conveyed in a duct, as well as measurements of the fluid flow and fluid fractions of mixed fluids are needed in a large number of industrial processes or applications. For example, in the cases of the extractive oil industry and the petrochemicalindustry, it is important to know, at any given time, the quantities of oil, water and gas flowingthrough a duct coming from an oil well. In addition, it is important to be able to identify given effluents, such pollutants, in process industries, such as the food industries, etc. This is the case in the oil industry, since the obtained data allows quantifying primary well production, as well as the success achieved with secondary extraction. In these wells high pressure fluid injection is used for recovery of remaining oil.
In order to carry on the above-mentioned measurements, sampling procedures are used in different production stages. That is to say, flow intervention is required to obtain proper sampling. The inventors have estimated that the data will be obtained in a non-invasive and non-destructive way, and that these data is obtained independently of the mixing state of the flowing fluids, which will provide important costs reductions benefits, as well as a reduction in the time needed to carry out the measurements. To this end, the inventors have established that Nuclear Magnetic Resonance turns out to be a non-invasive and non-destructive technique that can be used to obtain a flow meter and a fraction meter, thus enabling a device and procedure to simultaneously measure both the flow and the fraction of the fluids flowing through a pipe. The inventors know that when magnetic moments, such as the nuclear spins of hydrogen atoms, are introduced in an external magnetic field, they have a tendency to align along the magnetic field giving rise to nuclear magnetization, which spins from a precession about this magnetic field at a characteristic frequency known as the resonance frequency.
In this way, and as a consequence of the presence of the external magnetic field, the nuclear spins reach a new equilibrium state. The time required to reach this new equilibrium state, measured from the instant in which the nuclear system is introduced in the magnetic field, is known as the “Spin-Lattice Relaxation Time”, and is indicated as T1. T1 values depend on the many physical phenomena undergone by the spin system. Among these are the temperature, the system dynamics, the molecular structure in which the hydrogen atom exists, the molecular dynamics, the intramolecular and intermolecular interactions, and others. If the nuclear magnetization departs from its equilibrium state, its component perpendicular to the externally applied magnetic field decays away in a characteristic time known as “Spin-Spin Relaxation Time”, which is indicated as T2. T2 values depend also on many physical phenomena undergone by the spin system, among which include the temperature, the molecular structure, the molecular dynamics, and others, with these being perhaps those that are the most important. Particularly, in an heterogeneous system, such as in an oil and water fluid mixture, the hydrogen nuclei in the oil and molecules in the water are well differentiated by means of their spin-lattice and spin-spin relaxation times due to the various and different processes and physical phenomena undergone by the two types of molecules. Additionally, other relaxation processes may be accounted for. One of the most relevant ones is the so called “Rotating System Spin-Lattice Relaxation Time”, which is indicated as T1□. Nuclear Magnetic Resonance literature is replete with experimental techniques as to how to move the nuclear magnetization away from its state of equilibrium. Indeed, in this sense, it is known that many scientific works have been published previously to the innovations contained herein. For example, account has been given to the books “The Principles of Nuclear Magnetism” by A. Abragam (Clarendon Press, Oxford, 1961) and “Principles of Magnetic Resonance” by C. P. Slichter (Springer-Verlag, New York Heidelberg Berlin, 1990). In addition, account has been given to the published works of R. R. Enrst y W. A. Anderson in “The Review of Scientific Instrument”, Vol. 37, No 1, Page 93, 1966, and the work of R. Bageira de Vazconcelos Azeredo, A. L. Colnago y M. Engelsberg, namely “Analytical Chemistry”, Vol. 72, No 11, Page 2401, 2000. In order to have a flow meter to measure fluid flow and fluid fractions, and a procedure to record fluid flow and fluid fractions of a fluid flowing fluid in a duct, various techniques are available, one of which is a radio frequency pulse techniques. In this technique, a coil wound around the fluid to be measured and a series of pulses of alternating current applied to the fluid at the resonant frequency or at a frequency that is slightly shifted in order to move the nuclear magnetization away from its equilibrium state or position. Once the pulse ends, the magnetization returns to its equilibrium position, but does so in precession about the externally applied magnetic field. This precession induces an alternating voltage in the coil, which is referred to as the Nuclear Magnetic Resonance signal, whose amplitude is proportional to the number of hydrogen nuclei present in the fluid sample and whose temporal evolution depends on both spin-lattice and spin-spin relaxation processes. The information contained in the Nuclear Magnetic Resonance can be used to determine the fluid flow as well as the fraction of each of its components independently if these components are emulsified or phase separated.